Recent years have seen developing speech synthesis technology that converts text information into speech, speech recognition technology that recognizes the content of what a user says as text information, and natural language processing technology that recognizes the content indicated by sentences. Accordingly, interactive user interfaces (UIs) based on speech inputs have been gaining widespread use which apply the above-mentioned kinds of technology to allow users to operate a variety of home appliances such as television receivers and information devices such as personal computers through speech interaction.
There is an ongoing study on a mechanism that combines showing information by outputting speech with showing information by a different output method (e.g. showing display information such as an image and an animation) other than speech outputs to allow a user of the interactive user interface based on speech inputs to more intuitively recognize the information.